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Named extended ACL — allow the web, refuse the rest, in order
Enterprise Intermediate 3 devices 4 checked tasks 100 points Plan lab
Users may browse the intranet server and nothing else on it. Write a named extended ACL (permit web first, deny the rest and count the hits), place it as close to the source as the rules allow, and use the match counters to prove it is the web rule that is working. You build it in a browser, type real commands at each device, and every task below is
checked against the running configuration — so you find out it is wrong before anybody else does.
Open this lab in the simulator
The simulator runs in your browser with nothing to install. This lab is part of the full simulator: open it free for 7 days with a new account, then with a plan. It needs an account, which keeps your progress.
The scenario
Users may browse the intranet server and nothing else on it. Write a named extended ACL (permit web first, deny the rest and count the hits), place it as close to the source as the rules allow, and use the match counters to prove it is the web rule that is working.
Your role: a network engineer on the enterprise team. Level: Intermediate Done when: all 4 goals show as passed (100 points).
Network status
Devices: 1 router, 1 PC, 1 server, cabled as drawn. No Layer 1 or Layer 2 faults: every link is connected and up. R1 starts with addresses (G0/0 10.1.0.1/24, G0/1 10.2.0.1/24). User-PC is a host with 10.1.0.10/24, gateway 10.1.0.1. Intranet is a host with 10.2.0.10/24, gateway 10.2.0.1. Known problems
None: nothing is misconfigured. The network is simply not finished: what the goals list is what you have to build or secure. Goals
A named extended ACL exists (20 pts) It is applied inbound on the user-facing interface (20 pts) The user can browse the intranet (30 pts) The user cannot ping the server (only web is allowed) (30 pts) The activity, in order
A named extended ACL exists Why: This is the task that checks your configuration directly: the line must really be there, not just look right. Verify with: show running-config It is applied inbound on the user-facing interface Why: This is the task that checks your configuration directly: the line must really be there, not just look right. Verify with: show running-config The user can browse the intranet Why: Each goal is a state the lab can check on the running device. Verify with: show running-config The user cannot ping the server (only web is allowed) Why: Blocking traffic is half of security. You prove a block by showing the same ping that worked before now fails. Verify with: ping 10.2.0.10 Tips
Work in the order given: later goals depend on the earlier ones. After every change, run the verify command before moving on; do not guess. Stuck? Read the verify output first. It names the interface, neighbour or route that is wrong. Common mistake: Deny before permit Common mistake: Forgetting the implicit deny at the end Common mistake: Blocking return traffic Why this matters
Named ACLs are editable by sequence number and self-documenting. Extended ACLs match protocol, source, destination and port, so “allow web, deny the rest” is expressible — in the right order.
What you will be able to do
Write a named extended ACL
Place it inbound near the source
Use match counters to confirm which line matched
The network
ISR 2911, PC, Server — 3 devices in all, already cabled.
Gi0/0 10.1.0.1/24 Fa0 Gi0/1 10.2.0.1/24 Fa0 R1 User-PC 10.1.0.10/24 · gw 10.1.0.1 Intranet 10.2.0.10/24 · gw 10.2.0.1 Drawn from this lab: devices, cables, ports and the addresses already set. Device Model Address already set
R1 ISR 2911 configure it User-PC PC 10.1.0.10 / 255.255.255.0 gw 10.1.0.1 Intranet Server 10.2.0.10 / 255.255.255.0 gw 10.2.0.1
Cabling
R1 Gi0/0 ↔ User-PC Fa0 R1 Gi0/1 ↔ Intranet Fa0
What is configured at the start
These are already configured when the lab opens — including, where this is a troubleshooting lab, the fault itself:
R1 interface g0/0
ip address 10.1.0.1 255.255.255.0
no shutdown
exit
interface g0/1
ip address 10.2.0.1 255.255.255.0
no shutdown
exit Tasks, and how each one is checked
Every task is decided by reading the live network — a neighbour in FULL, a ping that succeeds, a line in the running configuration — not by looking for a keyword you typed. The same command shows you what the lab sees.
# Task Pts How to verify it yourself
1 A named extended ACL exists 20 On R1: show running-config contains the line(s) matching ip access-list extended \S+. 2 It is applied inbound on the user-facing interface 20 On R1: show running-config contains the line(s) matching interface GigabitEthernet0/0 … ip access-group \S+ in. 3 The user can browse the intranet 30 From User-PC, fetching http://10.2.0.10 must work (the browser, or curl http://10.2.0.10). 4 The user cannot ping the server (only web is allowed) 30 On User-PC: ping 10.2.0.10 must fail — the policy blocks it.
Stuck? Ask the coach
Tell the coach what you see or what you tried. It gives you a hint, not the answer, the way a senior engineer would. Included with a free trial or any plan.
Ask the coach
Common mistakes
Deny before permit
Forgetting the implicit deny at the end
Blocking return traffic
Reference solution
Try it yourself first — the lab checks your work either way. This is one configuration that makes every task pass, device by device:
R1 ip access-list extended USERS-IN
permit tcp 10.1.0.0 0.0.0.255 host 10.2.0.10 eq 80
deny ip any any log
exit
interface g0/0
ip access-group USERS-IN in
exit Where this is examined
CCNA (ACLs), Network+ (firewall rules), Security+ (access control).
This lab practises these topics in the zNetLaB certification courses:
Related labs
Where to start
The lessons all guided labs plans
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